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1 <br />�I <br />LDIVISION <br />3 <br />CONCRETE <br />03300 - CAST -IN -PLACE CONCRETE <br />U . CURING AND PROTECTION <br />A. 'General: Beginning immediate) after <br />Y placement, protect concrete from <br />premature drying, excessively hot <br />or cold temperatures, and mechanical <br />injury, and maintain with minimal moisture loss at relatively constant <br />temperature <br />for period necessary for hydration of cement and hardening of <br />concrete. Materials and methods <br />of curing subject to approval. <br />1. For concrete surfaces not in contact with forms, apply curring agent <br />as specified under Article 4, item F <br />of this specification section <br />immediately after completion of placement and finishing. Apply in <br />strict <br />r <br />accordance wtih manufacturer's recommendations. <br />2. Minimize moisture loss from surfaces placed against wooden forms or <br />metal forms exposed to heating by by <br />sun keeping forms wet until they <br />can be safely removed. After form removal, cure <br />time prescribed, concrete until end of <br />3. Continue curing for at least 7 days in case of all concrete except <br />high -early -strength concrete for <br />which eriod <br />days, p shall be at least 3 <br />B. Temperature, wind and humidity. <br />1. In cold weather -comply with ACI 306; in warm weather comply with A 305. P Y CI <br />2. Rate of temperature change. Keep changes in temperature of air <br />immediately adjacent to concrete during and immediately following <br />curing period as uniform as possible. Do not exceed 5u F. in an 1 <br />hour or 50 F. in any 24 hour period. Y <br />3. Slabs shall be cured with polyethylene. Cure concrete for 5 days at <br />minimum temperature of 70 F. Cure concrete <br />temperature of 500 F. No curingallowed when otemperature r 7 days at minimum <br />snbelow <br />500 F. <br />C. Protectio <br />n from mechanical injury: <br />1. During curing period, protect concrete from damaging mechanical <br />disturbances such as load stresses <br />, heavy shock vibration. Protect all finished concrete surfaces dfrom edamage b <br />construction equipment, materials, or methods, and by rain or running <br />water. Do not load self-supporting structures in such a way as to <br />overstress concrete, Y <br />5264 SECTION 03300 - 9 <br />